Some time before the series, she met Hitomi and her then boyfriend Kishida. Kishida have dumped Hitomi for Aiko which the two have start dating each other. Known is during their date, Kishida gave Aiko the same necklace he gave to Hitomi.
Aiko have somewhat a though looking personality when she was around with her boyfriend Kishida. She has been seen desperate about her boyfriend's brutal death caused by Hitomi.
Main article: Kishida Kishida was Aiko's boyfriend, which was known that Kishida broke up with Hitomi to be with Aiko. He gave her a pearled necklace when the two were dating before his death. It was seen that Aiko was very attached to Kishida, being around him every time, when he is killed during a roller coaster ride, she was crying desperately.
Main article: Hitomi The two knew each other before she and Kishida went to colleague. Evenly known that Kishida broke up with Hitomi to be with Aiko, the two remain to stay friends until Kishida's horrible death.
Main article: Reiko Reiko is Aiko's friend which they have met somewhere before the meeting of Hitomi and Kishida. Nothing is known about the two, but it is implied that the two used to be best friends after Aiko dated with Kishida.
Aiko has brown hair with a red head band around her forehead. She has gray looking eyes and wore a black furred jacket when she went with her friends and boyfriend to the amusement park Tropical Land.
The Murder In the Roller Coaster
Main article: The Murder In the Roller Coaster
Aiko was first seen with her then boyfriend Kishida, after that Kishida was shouting to Shinichi. She and Kishida were then been seen kissing each other and later entered the roller coaster. After that Kishida has been decapitated during the roller coaster ride, the police arrived after Kishida's brutal death. Aiko soon got the blame after that a knife was found in her bag which she denies that she has something to do with it. After that Shinichi has revealed that Hitomi was the one who have murdered Kishida, Hitomi revealed why she did it, leaving Aiko in tears.
The name Aiko (愛子) means literally "Love child" which can also be a reference meaning to the name Itoshigo which literally means "beloved dear child". It is popular female Japanese name, while it is a uncommon Dutch boys name that is extremely rarely used.